1. Field of the Invention
The present invention relates to a vehicle glass run, which is mounted on a door frame of a vehicle and a method of manufacturing the same. More particularly, the invention relates to a structure of a corner part and a method of manufacturing the same.
The present application is based on Japanese Patent Application No. 2000-251946, which is incorporated herein by reference.
2. Description of the Related Art
A conventional vehicle glass run mounted on the side door (frame) is disclosed in Unexamined Japanese Patent Publication No. Hei. 10-44786. The vehicle glass run is provided with extrusion parts for the roof and pillars, and the corner molding parts connecting those extrusion parts together. The extrusion parts and the corner molding parts are U-shaped in cross section. A door glass is slidably moved within and along the sliding grooves of the glass run. Sealing lips contact to the surfaces of the door glass, which are sealing between the inside and outside of the vehicle. Further, the sealing lips guide an upward and downward slide movement of the door glass.
The vehicle glass run is manufactured by the following process. Thermoplastic elastomer is extruded and cut to have a predetermined length to form extruded pieces. The extruded pieces are set in a mold. And, thermoplastic elastomer is injected into a cavity. The injected thermoplastic elastomer welds the surfaces of the terminal ends of the extruded pieces by heat and pressure, thereby connecting them. The thermoplastic elastomer is cooled and solidified. As a result, the corner molding parts connecting the terminal ends of the extruded pieces in an L shape are formed. The corner molding parts are shaped resembling the corners of the side door.
In the vehicle glass run, a reliable sliding movement of the door glass is folded with the side ends of the pillar-side extrusion parts. Accordingly, the U-shaped sliding groove must be deep. The merely supports the upper-side end of the door glass put thereinto. Attempt is made to design the roof-side extrusion part with a shallow groove to make the external appearance good. When the vehicle glass run is designed such that the grooves of the pillar-side and roof-side extrusion parts are different in depth, viz., the cross sectional shapes of them are different, and both the extrusion parts are connected by the corner molding parts which are various in cross sectional shape, the size of the pillar-side portion of the corner molding part is larger than the roof-side portion of the corner molding part.
Enlargement of the corner molding part implies that a distance from the gate position for injecting the thermoplastic elastomer to the terminal end of the extrusion part is increased. Accordingly, the thermoplastic elastomer cannot rapidly travel and reach the terminal ends of the extrusion parts, while keeping its high temperature. As a result, the thermoplastic elastomer cannot weld and connect the terminal ends of them by heat and pressure. If the heat welding of them is insufficient, a connecting strength at the connecting part between the extrusion part and the corner molding part decreases. As a result, there is a danger that both the parts are separated from each other with the sliding movement of the door glass.